1. Technical Field
The field of art to which this invention pertains may be generally located in the class of devices relating to valves. Class 137, Fluid Handling, United States Patent Office Classification, appears to be the applicable general area of art to which the subject matter similar to this invention has been classified in the past.
2. Background Information
It is known in the valve art to provide three-way and four-way valves for controlling the flow of fluid, either air or hydraulic oil, to a device which is to be controlled by fluid under pressure, as for example, another valve or a fluid cylinder. Heretofore, solenoid operated valves required a large solenoid thrust when the valve was used to control high pressure fluids, to overcome the spring pressure required to maintain the solenoid plunger in the closed position. The problem solved by the present invention is the elimination of the need of a high solenoid thrust in a solenoid operated valve, by the provision of a unique balancing means which balances the solenoid plunger.
An example of a prior art solenoid operated, three-way valve with pressure balancing is illustrated in U.S. Pat. No. 3,865,140. However, the solenoid operated valve disclosed in this patent does not provide a direct balancing means for the solenoid plunger or armature, and it involves a complicated hydraulic balancing structure which includes a tandem valving operation, valving orifices, and other associated structures.